Spinothalamic tract cells, identified by antidromic activation from the contralateral diencephalon, will be examined for covergence of visceral and somatic input. Visceral afferent input will be obtained by electrical stimulation of the greater splanchnic nerve. Fiber fractions of the splanchnic nerve which may elicit activity in spinothalamic tract cells will be determined by recording from the thoracic sympathetic chain. Adequate stimuli and receptive fields for cutaneous input will be determined using natural stimulation of the skin. Possible interactions between visceral and somatic input onto spinothalamic tract cells will also be examined. All experiments will be carried out on anesthetized cats with intact nervous systems.